1. Field of the Invention
This invention relates to a process for the production of interesterified glyceride oil or fat of high added value at cheap cost by the continuous interesterification of glyceride oil or fat in presence of a fatty acid, fatty acid ester or different glyceride oil or fat.
More specifically, the invention relates to an efficient process of the interesterification of glyceride oil or fat wherein the reaction is continuously performed without need of any dehydration in a reactor column packed with an alkaline high molecular weight lipase preparation capable of continuously and strongly catalyzing the interesterification of glyceride oil or fat in presence of a fatty acid, fatty acid ester or different glyceride oil or fat in such a very low moisture content condition that no reaction of this sort has hitherto been considered possible.
2. Description of the Prior Art
The interesterification of glyceride oils and fats is an effective means to modify the chemical composition and physical properties of these oils and fats for upgrading.
Both chemical and enzymatic processes are known for the interesterification. The chemical process of interesterification is carried out at high temperatures in presence of an inorganic catalyst, such as sodium metal or sodium methylate, and applied to the production of margarine, shortening, and other processed oils and fats.
However, the chemical process of interesterification not only requires severer reaction conditions as compared to the enzymatic process but is nonspecific to the positions of the triglyceride molecule and therefore applicable only to randomization. Accordingly, interesterified oils and fats thereby produced are upgraded and add values only to a limited degree. By contrast, in the enzymatic process of interesterification, the reaction proceeds in mild conditions and use of a position specific lipase can limit interesterification to a selected glyceride position or positions, so more added values can be expected with interesterified oils and fats. Many studies have thus been made in this field.
Japanese Patent Opening 52-104506 (Unilever) and others proposed a number of batch processes, each making use of an acidic or neutral lipase of low molecular weight from Rhizopus, Aspergillus or Mucor source. However, many of these proposed batch processes use a method in which the lipase can be activated only when aqueous solution of this enzyme is concentratively carried as such by a porous carrier, for example, activated carbon or celite. For water that is practically involved in the reaction system of these proposed processes, beside the aqueous solvent from the specified substrate solution, water that leaks out of the enzyme support provides a practically abundant additional water supply to the reaction system. Further, the above additional water supply adds with a large quantity of support used at every reaction batch and it is such additional water supply that gives rise to the intended reaction. The process proposed by the present invention is essentially different from these disclosures in this point.
On the one hand, continuous processes of the enzymatic interesterification are disclosed in European Patent Publication 0140542, Japanese Patent Opening 61-202688 (Novo), European Patent Publication 0170431, and European Patent Publication 0069599 (Unilever). In the processes disclosed by these patents, an acidic or neutral lipase of low molecular weight from Mucor, Aspergillus or Rhizopus source is used. The above enzyme is used as an enzyme preparation supported in the form of aqueous enzyme solution by a support such as CELITE. Or alternatively, the enzyme is immobilized on an adsorbent resin or ion exchange resin by adsorption and the resultant immobilized enzyme preparation is adjusted to a specified moisture content. Different from the very low moisture content range of the substrate solution as specified by the present invention, the above processes are characterized by the continuous reaction that occurs in abundant presence of aqueous solvent. Of the above disclosures, only Japanese Patent Opening 61-202688 explicitly describes about the moisture content of the substrate though only giving data for the moisture content of the substrate at the outlet of the reactor column. Namely, this patent specifies 3600 to 5000 ppm and 2800 to 3100 ppm moisture for the substrate output from the reactor column at the initial stage of reaction and after 400 hr continued reaction, respectively. Thus, the present invention definitely differs from the above disclosure in the following point. Namely, while in a trace moisture range as specified by this invention the alkaline high molecular weight lipase catalyzes interesterification strongly in a continuous process of long period, the low molecular weight lipase as disclosed in the above disclosure can effect almost no interesterification in such a trace moisture range. On the other hand, in the moisture range specified for the continuous reaction in the above disclosure, though the low molecular weight lipase may effect interesterification fully, the moisture is too high to have the alkaline high molecular weight lipase efficiently and satisfactorily catalyze the continuous interesterification process.